docs: def rotation_from_axes(x_axis, y_axis, z_axis):
          """Convert specification of axis in target frame to
          a rotation matrix from source to target frame.
  
          Parameters
          ----------
          x_axis : :obj:`numpy.ndarray` of float
              A normalized 3-vector for the target frame's x-axis.
  
          y_axis : :obj:`numpy.ndarray` of float
              A normalized 3-vector for the target frame's y-axis.
  
          z_axis : :obj:`numpy.ndarray` of float
              A normalized 3-vector for the target frame's z-axis.
  
          Returns
          -------
          :obj:`numpy.ndarray` of float
              A 3x3 rotation matrix that transforms from a source frame to the
              given target frame.
          """
          return np.hstack((x_axis[:,np.newaxis], y_axis[:,np.newaxis], z_axis[:,np.newaxis]))